Low RV fistula
High RV fistula
Middle fistulas are found between the two (Fig. 7.3).
A perineal surgical approach is more suited for low and middle rectal fistulas, while high fistulas are more easily repaired through a laparotomy.
Simple rectovaginal fistulas consist of small, low fistulas secondary to infection or trauma. These fistulas generally have healthy, well-vascularized surrounding tissue, which can be repaired with local techniques.
Rectovaginal fistulas are considered complex if they are large (>2.5 cm), high, or caused by inflammatory bowel disease. Recurrent fistulas are also considered complex due to their association with tissue scarring and decreased blood supply. To provide the best chance of successful repair, healthy, well-vascularized tissue needs to be introduced after resection of diseased tissue. Complex fistulas require more complicated surgical procedures for repair.
Based on anatomical considerations, the rectovaginal fistula can be classified into:
22.214.171.124 Pelvic Enterovaginal Fistula
These are usually because of previous hysterectomy, Crohn’s disease, diverticular disease, cancer, or operation. The fistula is usually from the ileum, sigmoid, or anastomotic site with posterior fornix of the vagina.
126.96.36.199 High Rectovaginal Fistula
These follow radiotherapy or pelvic operations of the rectum or uterus. The fistula is usually between the posterior fornix of the vagina with middle third of the rectum.
188.8.131.52 Midzone Rectovaginal Fistula
They may be secondary to obstetric cause, rectal neoplasia, or inflammatory bowel disease. The fistula is between the lower third of the rectum and midportion of the vagina.
184.108.40.206 Low Rectovaginal Fistula
These fistulas are seen secondary to obstetric injury, foreign bodies, and local trauma and pelvic repair surgery. The fistula lies at the level of anorectal ring.
220.127.116.11 Suprasphincteric and Transsphincteric Anovaginal Fistula
These are usually associated with anal gland infection, perirectal abscess, Bartholin’s abscess, Crohn’s disease, or previous anal surgery or anal anastomosis. The transsphincteric variety is becoming more common after ileoanal and coloanal anastomosis (Keighley et al. 2008).
7.4 Clinical Presentation
Patients usually report to doctor with the complaints of passage of flatus or liquid stools per vagina. In third world countries, many a times the females may report quite late because of social inhibitions. Some patients may complain of foul smelling vaginal discharge and frequent infections of the vagina and passive incontinence if the fistula is above the sphincter. In evaluation, always try to rule out inflammatory bowel disease and any pelvic malignancy. It is also quite important to know about any history of previous surgery or irradiation to pelvis or genitalia which may be the predisposing factor for the causation.
The local examination should comprise of vaginal examination, rectal examination, and surrounding tissue examination. One should look for stained undergarments; color, smell, and type of discharge; surrounding skin color changes; eczema; excoriation; or any pitlike defects in the anterior midline. Pinhole low fistulas may be asymptomatic.
Vaginal examination with a speculum may reveal darker mucosa in the fistula track, contrasting with the light vaginal mucosa. There may be visible stool in the vagina or one may encounter signs of vaginitis. Probing the tract should be avoided.
In rectal examination and proctoscopy, try to assess the integrity of sphincters, perineal body, the muscles, and tissues between the rectum and vagina. Try to locate the opening in the rectum by direct visual examination during proctoscopy or by bi-digital examination with one finger in the rectum and other in the vagina. In case of big defects, the two fingers meet each other at the site of defect. This method of examination can also give you the assessment of the strength of intervening tissue and mainly the thickness of the perineal body. A colonoscopic examination after bowel preparation should be an important part of the assessment in case of any suspicion of inflammatory bowel disease or malignancy. During the physical examination, an assessment of anal sphincter integrity will assist in surgical planning. There is often a coexisting fecal incontinence due to pelvic floor neuropathy and sphincter deficiency (Snooks et al. 1986).
Many a times the confusion may still be there about the exact anatomic location and nature of sphincter damage on the basis of clinical evaluation. It is very important for the surgeon to know the exact anatomic location and the status of sphincteric strength to plan the best modality of treatment.
7.5.1 Examination Under Anesthesia (EUA)
This may prove to be one of the most effective diagnostic tools in uncooperative patients and may even reveal better details in most of the patients and help to plan the most suited surgery. This will also allow you to take multiple biopsies to rule out an inflammatory bowel disease and malignancies.
7.5.2 Anorectal Manometry
It may provide some useful information in fistulas secondary to radiation or inflammatory bowel disease. These conditions will usually alter the resting anal pressure, squeeze pressure of sphincter, and compliance of the rectum to function as a reservoir.
7.5.3 Neurophysiologic Testing
Neurophysiologic testing with pudendal nerve terminal motor latency can be performed in selected instances, but it hardly has any prognostic significance, hence not performed in most of the centers (Saclarides 2002).
7.5.5 Barium Enema
This investigation can give general information about the health of the colon and rectum. This investigation, however, may fail to identify fistula in many patients, hence at present not practiced in most of the centers.
7.5.6 Computed Tomography (CT) Scan
A CT scan of the abdomen and pelvis with oral contrast may help to pick up the phlegmon or a neoplastic mass and detect the position of the gut responsible for a fistula.
7.5.7 Endoanal Ultrasonography (EAUS)
It is a very good investigative tool in patients who complain of incontinence along with complaints suggestive of an RVF (Figs. 7.4 and 7.5). Ultrasound can identify internal anal sphincter as a uniform hypoechoic circle under the submucosa. Defects can be easily picked up in the internal anal sphincter with the use of EUAS, but defects in the external sphincter are difficult to appreciate. The reason being that external sphincter fibers are hyperechoic, striated, and more loosely arranged in circular pattern.
Transrectal ultrasound image demonstrating a fistula highlighted with hydrogen peroxide. Arrow is showing the site of fistula
Endoanal ultrasound 2 arrows show the area with a breach in sphincter
The normal thickness of the perineal body as measured from anal mucosa to posterior vaginal wall is 12 mm, and obstetric injuries usually cause thinning of the muscle within perineal body and shortening of the height of the high-pressure zone of the anus. EAUS is a good investigation to pick up these changes (Saclarides 2002). However, some studies report that initial evaluation with EAUS is not satisfactory (Choen et al. 1991), but its diagnostic accuracy has improved with technical advances in ultrasonography including the use of hydrogen peroxide (H2O2) as a contrast agent and 3D reconstruction (Cheong et al. 1993; West et al. 2004). The image is no longer limited to axial phone in 3D-EAUS, but it is possible to cut across any part of the data in the coronal, sagittal, or oblique plane (Fig. 7.6a, b). The H2O2-enhanced 3D-EAUS is expected to diagnose anal fistula with high accuracy. Kim and Park (2009) concluded in their study on 3D-EAUS assessment of an anal fistula with and without H2O2 enhancement on 61 patients that 3D-EAUS is highly reliable in the preoperative evaluation of anal fistula. The use of H2O2 for enhancement offers some benefits, although it did not significantly improve the diagnostic accuracy in this study. The selective use of H2O2 may be economical and reliable in difficult cases.
(a, b) 3D endoanal ultrasound demonstrating fistula
7.5.8 Magnetic Resonance Imaging (MRI)
The test creates images of soft tissues in a patient’s body. MRI can show the location of a fistula, as well as involvement of pelvic organs or the presence of a tumor (Fig. 7.7a, b). Comparative studies of endoluminal ultrasonography and endoluminal MR imaging have comparable positive predictive values in revealing the location of anovaginal and rectovaginal fistulas (Stroker et al. 2002).
(a, b) MRI demonstrating RVF. Arrow shows the fistula tract
7.5.9 Endoanal MRI
Endoanal MRI provides high-resolution multiplanar images of the anal canal, the rectum, and the vagina. The T2-weighted sequences can depict lesions with high signal intensity such as fistulas and fluid collection. Studies have shown that endoanal MRI is an excellent modality for the assessment of simple as well as complicated anovaginal fistulas and allows evaluation of anovaginal fistulas and additional abnormalities such as abscesses within the rectovaginal septum secondary perianal fistula tracts and sphincter damage (Dwarkasing et al. 2004).
It is important to give a trial of conservative management to fistulas with a low discharge, small opening, and healthy perineum. Many such fistulas may close spontaneously. The surgical approaches for such patients are numerous. The options are determined by the etiology of the fistula, location, size, quality of the surrounding tissue, and previous attempted repairs. Most surgical approaches can be classified as either local or abdominal. Local repairs are most useful for low to middle rectovaginal fistulas and include transanal, vaginal, and perineal approaches. Abdominal operations are most useful for high rectovaginal fistulas. Either approach may require the use of healthy muscle or tissue for transposition.
7.6.1 Medical Management
This is helpful in RVFs secondary to obstetric or operative trauma or fistulas complicated by secondary infection. Use local wound care, drainage of infectious material, and antibiotics till the infection settles. Allow tissues to heal for 6–12 weeks. Many fistulas may heal completely and require no further treatment. Fistulas which persist can be repaired at a later date when the tissue is supple and infection is completely controlled.
In patients with IBD, appropriate medical therapy should be started. Repair of RVF can be carried out even when the patient is on steroids but with the understanding that chances of recurrence are high. Some patients can maintain RVF repair while on antimetabolites like 6-mercaptopurine or azothioprine. Some fistulas heal completely on infliximab but most improve symptomatically. If the patient presents with significant colonic involvement and anal stricture, then a fecal diversion should accompany the fistula repair.
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7.6.2 Surgical Treatment
RVFs which do not settle with conservative management will finally need one or the other types of surgery for the long-term cure. It is important to know that RVFs originating from radiation therapy, IBD, and stapling procedures are quite difficult to treat surgically. A proper evaluation, an appropriate selection of surgical procedure, and an experienced hand to tackle with the problem would be worthwhile to save the patient from the misery of repeated surgeries. Broadly surgical approaches may be perineal or abdominal as described under.
A proper planning of the procedure based on evaluation would be invaluable. Decide beforehand what approach you are going to adopt after assessing the anatomy, physiology, physical examination, and radiology of the patient. Discuss in detail with the patient and the attendants about the chances of recurrence, stoma, and complications of the operative procedures. Lack of planning will invariably lead to many confusions regarding positioning and type of anesthesia.
Optimization and preoperative preparation
Try to optimize patient’s nutritional status and anemia before contemplating any repair. Make sure the disease is under control in patients with IBD, and steroids and immunosuppressants have been weaned to minimal possible dose. Ensure that you have waited enough for the trial of conservative management. The gut is cleaned with mechanical bowel preparation before planning any surgery. Give a third-generation cephalosporin as an intravenous prophylactic antibiotic at the time of induction after test dose or within an hour before surgery. In case there is any history of irradiation to the pelvis, preferably use ureteral catheters to aid in dissection. Vaginal lumen is cleaned with an antiseptic solution and urinary bladder is catheterized.
The most popular position used by the surgeons all over the world still continues to be a lithotomy position. Various modifications can be made as per the requirement or the approach used. However, if one plans to go for transanal repair, then a prone jackknife position with the buttocks stripped apart will make the procedure more comfortable and surgeon friendly.
General anesthesia for abdominal approach and spinal anesthesia for perineal approach would be appropriate. Remember always to repeat your digital rectal examination under anesthesia and finalize your plan. Many times you may get the most important information by EUA which you missed otherwise.
18.104.22.168 Transanal Approaches
22.214.171.124.1 Mucosal Advancement Flap Repair
This procedure was originally described for repair of fistula in ano. It is a flap composed of mucosa, submucosa, and a portion of internal sphincter muscle used to cover the fistula defect. This is one of the commonly employed procedures for a low RVF. Patient is catheterized and placed in prone jackknife position. Infiltration with adrenaline has become controversial as some believe that it may make the tissue soggy and more prone to ischemia (Keighley et al. 2008). In this procedure, a trapezoid-like flap for 4 cm cephalad is mobilized (Fig. 7.8a). The base of the flap should be twice the width of the apex. This helps to keep the flap well vascularized. The distal end of the flap with the fistula is then excised (Fig. 7.8b) and the fistula dissected through the septum into the vaginal opening and sent for histological examination. The defect in the vagina is closed in two layers or may be left open for drainage (Fig. 7.8c, d).
(a–d) Mucosal advancement flap repair
If levators can be mobilized and closed over vaginal defect, the risk of ischemic breakdown decreases. The rectal advancement flap is then used to cover levatoroplasty and is sutured to the distal part of incision in the anus with an absorbable suture.
The literature reports different success rates with this approach. The reasons are multifactorial like previous operations, Crohn’s disease, preexisting sphincter status, and type of fistula. The success rates are reported in the range of 63–96 % in various studies (Sonoda et al. 2002; Kodner et al. 1993; Tsang et al. 1998). The studies have also proven beyond doubt that adding sphincteroplasty to this repair in patients with sphincter disruption, the success rates may go up to 95 % (Khanduja et al. 1999).
The proponents of this procedure propagate that intrarectal pressure increases at the time of defecation, so this type of repair addresses rectal defect in a more appropriate way, so chances of repair to last are better than transvaginal repairs.
126.96.36.199.2 Transanal Sleeve Advancement Flap (TSAF)
This procedure is ideally suited for patients with RVFs secondary to Crohn’s disease but with disease-free rectum. This is also considered to be a better approach for recurrent fistula complicated by anorectal stenosis. This procedure is done in lithotomy with a lone star retractor applied. The coring of fistula is done from the vaginal site. In the anal canal, a circumferential incision is made at the level of dentate line just below the fistula. One more circumferential incision is made approximately 3 cm above toward the rectum. Upper end-cut edges are held with series of sutures (Fig.7.9a). The dissected cylindrical rim is sent for histology. The anorectum is mobilized circumferentially to mid-sacral level to avoid any tension on the anastomosis. A coloanal anastomosis is made (Fig. 7.9b) and a drain is put through excised fistula site. Some surgeons may prefer to remove a sleeve of mucosa and submucosa only instead of whole thickness of anorectum.
(a, b) Transanal sleeve advancement flap (TSAF)
This procedure was first reported by Hull and Fazio in 1977. They subsequently updated it, and in their experience at Cleveland clinic, 12 patients with RV fistula with severe Crohn’s disease were operated, and 1 year after surgery, 8 patients showed full recovery. The authors are of the opinion that this procedure can be offered to some patients with severe Crohn’s fistula with a relatively normal rectum particularly when the only alternative left is total proctocolectomy and a permanent stoma.
188.8.131.52.3 Transanal Endoscopic Microsurgery (TEM)
The proponents of this approach believe that TEM is an ideal surgical approach to remove the fistula and the surrounding scar tissue. In this approach, you don’t make any incision in the perineum, so the chances of damaging sphincter are completely avoided, and the vision inside the rectum is magnified; thus, chances of identifying the fistula comfortably are more.
In prone position, RVF is identified after introducing a proctoscope, with a soft tube of small caliber introduced through the vagina or with the use of methylene blue. The vagina is then packed with gauze to avoid carbon dioxide (CO2) leakage.
The fistula tissue is widely excised till healthy margins are seen under three-dimensional vision of TEM. When dissection of the septum is complete, the TEM instrumentation is temporarily removed.
Use finger dissection to complete the dissection of the aboral part of the septum until the sphincter fibers are reached. For technical reasons, this part of the operation cannot be performed by TEM. The dissection of this part of the septum is easy once the correct plane is identified.
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